1. Technical Field
The present disclosure relates to a two-fluid nozzle spraying apparatus which atomizes a liquid using a gas.
2. Description of the Related Art
Nozzles for atomizing liquids are widely used in, for example, space/material cooling apparatuses, humidifying apparatuses, chemical solution dispensing apparatuses, combustion apparatuses, and dust control apparatuses. The atomization nozzles can be broadly divided into a single-fluid nozzle and a two-fluid nozzle. The single-fluid nozzle atomizes a liquid by spouting the liquid from a micro aperture. The two-fluid nozzle atomizes a liquid, using a gas such as an air, nitrogen, steam, etc. Comparing the single-fluid nozzle and the two-fluid nozzle, in general, the two-fluid nozzle is superior to the single-fluid nozzle in atomization performance because the two-fluid nozzle atomizes a liquid using energy of a gas.
As an example of the two-fluid nozzle which atomizes a liquid, for example, Japanese Unexamined Patent Application Publication No. 2001-149822 (PTL 1) discloses a two-fluid nozzle. The two-fluid nozzle disclosed in PTL 1, as illustrated in FIG. 4, has a triple-barrel structure comprising inner barrel 40, middle barrel 41, and outer barrel 42. Inner barrel 40 is formed of proximal barrel 43 and distal barrel 44 coupled with each other. A hollow portion of inner barrel 40 is referred to as center air passageway 45. An annular intermediate passageway between inner barrel 40 and middle barrel 41 is referred to as liquid passageway 46. An annular outer passageway between middle barrel 41 and outer barrel 42 is referred to as outer air passageway 47. Proximal opening 47a of outer air passageway 47 and proximal opening 45a of center air passageway 45 are connected to an air supply main not shown. Thus, low pressure air from a pneumatic pressure source configured of a blower not shown is introduced into proximal opening 47a and proximal opening 45a via the air supply main. Proximal opening 46a of annular liquid passageway 46 is connected to a water supply main not shown. Pressurized water from a liquid reservoir not shown is introduced into proximal opening 46a via the water supply main and a pump.
Distal barrel 44 included in inner barrel 40, middle barrel 41, and outer barrel 42 include distal portions 40b, 41b, and 42b, respectively, at respective distal ends. Distal portions 40b, 41b, and 42b have openings 40a, 41a, 42a, respectively, which are positioned collinearly along axis L. Opening 41a of middle barrel 41 is positioned within opening 42a of outer barrel 42. Opening 42a is a spout. Opening 40a of inner barrel 40 is positioned within opening 41a of middle barrel 41.
In inner barrel 40, distal barrel 44 is screwed into and connected to proximal barrel 43. Inner barrel 40 has inner barrel opening 40a at the tip, and small-diameter orifice 44a formed in the center of distal barrel 44 in the direction of axis L. Generally opposed two recessed grooves 44c are formed in distal surface 44b which define the perimeter of opening 40a of inner barrel 40.
Distal portion 41b of middle barrel 41 has a conical external surface, and an internal surface having step 41c. Middle barrel 41 has, on the distal end side, a small-diameter hollow portion having a same diameter as and communicating with opening 40a of inner barrel 40. Middle barrel 41 has opening 41a at the tip. Opening 41a has a smaller diameter than the small-diameter hollow portion of middle barrel 41.
Step 41c in middle barrel 41 abuts distal surface 44b of inner barrel 40 such that step 41c and grooves 44c form three liquid swirling communication passageways 48. Liquid swirling communication passageways 48 open to a distal hollow portion of inner barrel 40 and communicating between the distal hollow portion of inner barrel 40 and a distal hollow portion of middle barrel 41. A distal hollow portion formed and communicating between inner barrel 40 and middle barrel 41 is referred to as first mixing chamber 49.
Distal portion 42b of outer barrel 42 is positioned widely spaced from distal portion 41b of middle barrel 41. Second mixing chamber 50 is formed between distal portion 41b of middle barrel 41 and distal portion 42b of outer barrel 42. Second mixing chamber 50 communicates with outer annular air passageway 47. Opening 42a, which is the spout, is located in the tip center of outer barrel 42.
In the nozzle as configured above, initially, water that enters liquid passageway 46 is swirled as it passes through liquid swirling communication passageways 48 and the swirl flow enters first mixing chamber 49. Thus, the water has been put through primary atomization by being swirled. The water that entered first mixing chamber 49 in a form of the swirl flow impinges and mixes with an air from a blower which has passed and spouted from orifice 44a of center air passageway 45. Thus, the water has been put through secondary atomization by impinging and mixing with the air, and a gas-liquid mixed fluid spouts from opening 41a of middle barrel 41 into second mixing chamber 50.
The gas-liquid mixed fluid resulted from the secondary atomization impinges and mixes, in second mixing chamber 50, with an air from a blower that enters through outer air passageway 47. A gas-liquid mixed mist resulted from the tertiary atomization in this manner in second mixing chamber 50 is sprayed through opening 42a, which is the spout, of outer barrel 42. In particular, owing to second mixing chamber 50 being a large space, the air that entered second mixing chamber 50 through outer air passageway 47 uniformly impinges and mixes with the gas-liquid mixed fluid that entered through opening 41a and the gas-liquid mixed fluid is also swirled, thereby uniformly atomizing water droplets (see PTL 1).